Haec dies (Psalm 118:24,1) – Perotin

Psalm 118:24,1 [Latin Vulgate: Psalm 117:24,1]  

²⁴ This is the day that the Lord has made; let us rejoice and be glad in it.

¹ O give thanks unto the Lord; for he is good: because his mercy endureth for ever.

Haec est dies quam fecit Dominus; exsultemus, et laetemur in ea. Confitemini Domino, quoniam bonus, quoniam in saeculum misericordia ejus.

Haec est, composed by Pérotin (fl. c. 1200)

^Performed by Cantica of the Czech Republic